Cutaneous larva migrans, or creeping eruption, is a skin infestation by a larval nematode worm. The rash is caused by the burrowing of hookworm larvae through the skin. The larvae hatch from dog or cat faeces, mature in the soil and then penetrate human skin.
Patients develop several centimetre long red, very itchy, twisting tracks in and under the skin. Large blisters may form later. Secondary bacterial infection of skin may occur due to damage by both the larvae and scratching.
A skin biopsy is sometimes used to make the diagnosis. Treatment involves medication by mouth and ointment to kill the larvae, and other creams to ease the skin irritation.
The larvae cannot mature in humans, and die after several weeks, then the skin tracks slowly heal.